1. Field of the Invention
The present invention lies in the field of object protection by the application of an electrical field and also in the field of the magnetic treatment of feed water or similar liquids for the purpose of preventing the deposition of calcareous material, feed water scale or the like on the inner surfaces of conduits, casings, and the like, and is especially directed to the combined magnetizable impeller flow and magnetic field treatment of flowing water without recourse to chemical conditioning agents which have been heretofore employed to sequester, chelate, or solubilize the calcareous matter carried in the water.
2. Description of the Prior Art
For the purpose of passivation or of object protection of ferrous surfaces to inhibit corrosion by water flowing in contact with such surfaces, electrical fields and magnetic fields have been tried in many different parts of the world and for a long time.
For example, Cabell in U.S. Pat. Nos. 68,041, 71,451, 73,872, 304,989 and 409,136 has proposed the introduction of magnetic elements into the boiler to prevent calcareous scale build-up.
More recently, Vermieren in U.S. Pat. No. 2,652,925 and in Belgium Pat. No. 460,560 granted Nov. 30, 1945 describes a magnetic apparatus for water treatment to prevent calcareous deposits in which several elongated electromagnets are placed in a cylindrical casing and the water passes first upwardly between and around these electromagnets from an incoming central axial path, out and around, then downwardly and finally again upwardly on the outside of the electromagnets to thereby provide a sinuous and turbulent flow path which also aids in preventing encrustation. This magnetic device is sold commercially throughout the world.
Electrostatic treatment has also been widely practiced as shown for example in the British Pat. Nos. 601,576 and 601,580 published May 7, 1948 both granted to the Dubilier Condenser Company, and in the following typical U.S. Pat. Nos.: Heller, 3,256,168; Banks, 3,379,629, Locke et al, 3,409,530, Bremerman, 3,620,951, Evans, 3,798,142.
During the past few years an electrostatic scale control device has been marketed by Worthington Corporation, Harrison, N.J., and is described in an article in 1973 in Plant Engineering Magazine by Leo Spector, Managing Editor, the article entitled, "Breakthrough in Fluid Technology", "Electrostatic Scale Control". This Worthington device consists of two main elements: a cylindrical chamber through which the untreated water flows and a voltage control unit. At the center of the chamber is a wire-wrapped core covered by a dielectric sheath; it is the positive electrode. The outer metal shell serves as the negative electrode. Water enters the chamber at the bottom and spirals around the core as it travels upward to the outlet. While the water is in the chamber, it is subjected to an electrostatic field of 3,400 volts. Power requirement if negligible (about 2 to 3 microamps as a result of dielectric losses); it's the static-field voltage that does the trick. The unit works best with untreated water. It is not recommended for use with water that has been softened or chemically treated, nor at liquid temperatures over 190.degree. F. The unit was successfully applied to promote scale removal and inhibit its formation in compressor and engine cooling jackets, heat exchangers, hot and cold water lines, air conditioning systems and a host of other traditional, as well as untraditional, situations. In each instance, water flow and heat transfer properties were improved and maintenance problems either minimized or eliminated.
One of the difficulties with the unit is scale removal is slow and takes several months even though it is abetted by the spiral water flow pattern.